The present invention is intended to be applied in a plant for the sorting of individual timber pieces of different dimensions and/or qualities into a number of sorting compartments superposed over one another.
In prior art plants of the above-mentioned type, the individual sorting compartments are represented by approximately horizontal conveyors of a considerable length, of the order of magnitude of 50-100 m or possibly more. These conveyors are superposed over one another with a spacing of approximately 30-40 cm. The number of sorting compartments in the vertical direction may be large, often as many as 30-50 in number.
A downwardly moving conveyor runs along the infeed ends of the sorting compartments and conveys the individual timber pieces up to a given, predetermined sorting compartment where the timber piece is discharged by means of a transfer device and is fed into the selected sorting compartment.
Prior art plants have suffered from excessively low capacity, since the transfer of the individual timber pieces from the downwardly moving conveyor to each respective sorting compartment takes excessively long time.
In order to attempt to increase the capacity of the plant, the time available for infeed of each individual timber piece into a specific sorting compartment has been increased. This has been realised by means of an increase of the linear transport length for each timber piece on the downwardly moving conveyor from the uppermost sorting compartment to the lowermost. In order to achieve this, the downwardly moving conveyor has been placed at an inclination in that the individual sorting compartments do not begin in a vertical plane, but in a plane which inclines to the vertical. This has been achieved in that an upper sorting compartment extends out beyond a subjacent sorting compartment. The downwardly moving conveyor follows the infeed ends of the sorting compartments and displays considerable inclination in relation to a vertical plane.
The downwardly moving conveyor has a number of chains on which the timber pieces lie flat with the longitudinal direction of the timber pieces approximately at right angles to the direction of movement of the chains. This implies that the timber pieces incline in the same manner as the chains, for which reason the front edges of the timber pieces, seen in the direction of movement, are constantly located on a lower level than their rear edges. This inclination of the timber pieces is highly advantageous, or even necessary, when the timber pieces are to be transferred from the downwardly moving conveyor to each respective sorting compartment.
For feeding the individual timber pieces to the downwardly moving, inclining conveyor, use has been made of a conveyor which moves approximately horizontally and in the same direction as the downwardly moving conveyor. The transfer between these two conveyors was put into effect in a quite simple manner.
The above-described arrangement with sorting compartments, where an upper sorting compartment extends with an end portion out beyond the end of a subjacent sorting compartment implies that the length of the lowermost and shortest sorting compartment is determined by the requirements on the capacity of the plant and that, as a result, all superjacent sorting compartments will, in principle, be unnecessarily long and costly and in which the uppermost sorting compartments will be far too long.
As an attempt to obviate the need for these excessively long sorting compartments, the objective is to place the infeed ends of the sorting compartments and the downwardly moving conveyor in mutually parallel vertical planes. This requires that the downwardly moving conveyor be provided with projecting carriers which each are to carry a single timber piece. The previously known technique of feeding the downwardly moving conveyor cannot be employed in such a configuration.
Problem Structure
The present invention has for its object to design the feeding arrangement intimated by way of introduction such that it can, with high capacity, feed a substantially vertical downwardly moving conveyor with projecting carriers, at the same time as the timber pieces carried by the carriers can be given an orientation which is favourable when the timber pieces are subsequently transferred to each respective sorting compartment. In particular, the present invention has for its object to design the arrangement according to the present invention such that it affords an extremely high work rate and a high level of operational reliability.
Solution
The objects forming the basis of the present invention will be attained if the carriers incline obliquely downwards in a direction out from the downwardly moving conveyor, that a curved guide space defined by guide rails is disposed to overlap an upper region of the downwardly moving conveyor with a lower end portion, and that the angle of curvature of the guide space is so great that the upper side of a timber piece coming to the guide space will be turned downwards when the timber piece rests on a carrier.